Device for balancing axial thrust on the impeller shaft of pumps

Claim 1

In a centrifugal pump having a casing providing a highpressure chamber, and at least one impeller disposed in said chamber and mounted on a pump shaft, a device for balancing axial thrust on the pump shaft comprising an enclosure provided axially adjacent said high-pressure chamber and defining therewithin a low-pressure chamber communicating with the suction side of the pump, an axially displaceable thrust drum provided around said pump shaft between said high-pressure and low-pressure chambers, a balancing disk disposed around said pump shaft within said enclosure and having a cross-sectional area greater than that of said thrust drum, said balancing disk being substantially integral with said thrust drum so as to be axially displaceable therewith, a thrust disk firmly mounted on said pump shaft at the side remote from said thrust drum with respect to said balancing disk and arranged in face to face relationship to the balancing disk, said balancing disk and said thrust disk defining therebetween a balancing chamber which is in communication with said high-pressure chamber through an annular clearance provided between the outer peripheral surface of said pump shaft and an axial bore provided through said thrust drum and said balancing disk and which is in communication with said low-pressure chamber through a clearance between the outer peripheries of said balancing and thrust disks, an annular axial projection integrally provided on the radially inner periphery of said balancing disk and extending toward the opposing face of said thrust disk to define an annular gap between the projection and the thrust drum, said gap communicatively connecting said annular clearance with said balancing chamber, and means providing an axial fluid passage through said thrust drum and said balancing disk, with said passage connecting said high-pressure chamber and said balancing chamber.